Bulb socket and method of producing same

Abstract: A bulb socket that avoids the various disadvantages caused by insert molding of a terminal of a complicated shape and also satisfies characteristics required for different portions of the terminal. A housing body (11) is made of a plastic material and includes a socket housing (12) for receiving a base portion (3) of a bulb (B) and a connector housing (13) for receiving a feeder connector. Each connector-side terminal (20) is of a generally L-shape and has a connector tab portion (22) and a relay tab portion (21) extending perpendicularly from this connector tab portion. Bulb-side terminals (30) are provided in the socket housing (12) at corner portions thereof in opposed relation to each other and function to mechanically hold the base portion (3) of the bulb (B), and also function to electrically contact lead wires (4) on the base portion (3), respectively. This bulb-side terminal (30) has a relay terminal portion (36) formed at a lower end thereof, which portion can be press-fitted on the relay tab portion (21) of the connector-side terminal.

Description: This invention relates to a bulb socket with a connector, and more particularly to a bulb socket having an improved terminal construction, as well as a method of producing such a bulb socket. In a bulb socket of this kind, a connector housing is formed integrally with a socket housing of a plastic material, and terminals are provided therein. Conventionally, this terminal includes an integral bulbside terminal portion exposed in the socket housing for contact with a bulb and an integral connector-side terminal portion exposed in the connector housing for contact with a feeder connector, and this terminal is fixed to the housing by insert molding during the molding of the socket housing. In the bulb socket of the above construction, however, the terminal has a complicated shape, and therefore there has been encountered a problem that the cost of a mold for insert molding is high. Because the terminal is large in size and is complicated in shape, the dimensional accuracy of the terminal is poor. As a result, there have arisen problems in that resin flows into the terminal during insert molding, the terminal interferes with and may be deformed by a mold, and the retaining of the terminal by the mold becomes inadequate, so that the deformation of the terminal by a resin injecting pressure, as well as an improper flow of the resin, can easily develop. Moreover, because of the complicated shape of the terminal, it is, in some cases, difficult to use an automation system employing a part feeder, which is disadvantageous from the viewpoint of manufacturing costs. Furthermore, since the terminal is of an integral construction formed from a single electrically-conductive plate, the bulb-side terminal portion for contact with the bulb and the connector-side terminal portion for contact with the connector are made of the same material. However, for example, the connector-side terminal portion should preferably have a plate thickness of about 0.6 mm in connection with the associated connector, whereas the bulb-side terminal portion should preferably have a plate thickness of about 0.4 mm to secure a contact pressure with the bulb. Thus, despite the fact that the characteristics required for different portions are different, these could not be satisfied with the conventional terminal. JP-U-01 086085, an English language summary thereof can be found in EP-A-0 668 638, discloses a bulb socket from which the present invention starts from. This known bulb socket has a main body formed with a bulb receptacle in which a bulb is mounted and a connector receptacle in which a feeder connector for supplying electric power is mounted. Bulb receptacle and connector receptacle are arranged such that the main body has a substantially L-shaped form. A bulb terminal and a connector terminal electrically connectable with the bulb and a feeder connector, respectively, are inserted and assembled in the main body. The connector terminal includes a connector tab which is in the form of a long and narrow plate member engageable with the feeder connector, and a holder electrically connectable with a bulb terminal. The connector terminal is mounted in the main body by inserting the connector tab through an insertion hole from a recess formed in the outer surface of the main body, so that the leading part of connector tab projects into the connector receptacle and the holder is disposed in the recess. The bulb terminal includes besides a pair of bulb holders a tongue portion which is provided below the bulb holders and in the form of a long and narrow plate member electrically connectable with the connector terminal. The bulb terminal is mounted in the main body by inserting the tongue portion from an opening of the bulb receptacle to the recess through an insertion hole and by engaging the tongue portion with the holder. After mounting the terminals in the main body, an insulating sealing agent is filled in the recess to cover tongue portion and holder. This prevents penetration of water from the outside of the main body, thereby preventing occurrences of corrosion and short-circuit of the terminals. However, the bulb socket according to this prior art has a likelihood that the sealing agent filled in the recess enters into bulb receptacle and connector receptacle through clearances between walls defining the insertion holes and the terminals, to thereby deposit on the surface of the bulb holder and connector tab. This causes contact failures between the bulb and the feeder connector. Furthermore, for assembling this known bulb socket besides the mounting steps of the terminals inside the main body an additional step of filling the sealing agent into the recess is necessary, accompanied by a waiting period until the sealing agent has cured. Thus, providing bulb sockets according to the prior art either makes it necessary to incorporate the respective terminals during molding, that is, to carry out a so called insert molding wherein terminals are beforehand set in a mold, said insert molding having the disadvantage that there is no satisfactory resin flow and the terminals are liable to be deformed. Another approach is to insert the terminals into an already prepared (molded) housing and to fix same by means of a filler material, as it is shown in JP-U-01 086085. It is thus an object of this invention to provide a bulb socket which can overcome the various problems caused by insert molding of a terminal of a complicated shape, and can reduce the cost by automating the manufacture, and can satisfy characteristics required for different portions of the terminal. It is also an object to provide a method of producing such a bulb socket. According to the present invention, there is provided a bulb socket comprising a bulb socket for holding a bulb and for providing an electrical connection between a feeder connector and an electrical lead on the bulb, comprising: an L-shaped housing body formed of an electrically insulative material, said housing body comprising: a connector housing portion connectable with a feeder connector, a socket housing portion for receiving and retaining a light bulb, and a connecting cavity connecting the connector housing portion and the socket housing portion, wherein a longitudinal axis of the connector housing portion is substantially perpendicular to a longitudinal axis of the socket housing portion; at least one electrically conductive connector-side terminal mounted in the connector housing portion and connectable with said feeder connector, and having a relay tab portion extending into the connecting cavity; and at least one electrically conductive bulb side terminal mounted in said socket housing portion and comprising: a feeder electrode for contacting an electrical lead on a bulb inserted in the socket housing portion, and a relay terminal portion extending into the connecting cavity and being electrically connected to said relay tab portion. Said bulb socket furthermore being characterized in that terminal grooves are integrally formed in the connector housing portion and wherein the at least one connector-side terminal further comprises projections that are press-fittable into said grooves to mount the connector-side terminal in the connector housing portion. According to the present invention, a method of producing a bulb socket for holding a bulb and for providing an electrical connection between a feeder connector and an electrical lead on the bulb, comprises: providing an L-shaped housing body formed of an electrically insulative material, said housing body comprising: a connector housing portion connectable with a feeder connector, a socket housing portion for receiving and retaining a light bulb, and a connecting cavity connecting the connector housing portion and the socket housing portion, wherein a longitudinal axis of the connector housing portion is substantially perpendicular to a longitudinal axis of the socket housing portion; mounting at least one electrically conductive connector-side terminal in the connector housing portion for connection with said feeder connector such that a relay tab portion of said connector-side terminal extends into the connecting cavity; and mounting at least one electrically conductive bulb side terminal in said socket housing portion such that a feeder electrode for contacting an electrical lead on a bulb inserted in the socket housing portion extends into said socket housing portion and a relay terminal portion for an electrical connection with said relay tab portion extends into said connecting cavity, said method being furthermore characterized by forming terminal grooves in said connector housing portion upon providing said L-shaped housing body, forming projections at the at least one connector-side terminal, and press-fitting said projections into said grooves to mount the connector-side terminal in the connector housing portion. In the bulb socket, two kinds of terminals are used, that is, the connector-side terminals and the bulbside terminals, and therefore a material can be selected so as to satisfy the characteristics required for each of the terminals. This is a first benefit of the present invention. Specifically, by forming terminal grooves in the connector housing portion upon providing said L-shaped housing body, forming projections at the at least one connector-side terminal, and press-fitting said projections into said grooves to mount the connector-side terminal in the connector housing portion, neither an insert molding nor a recess to be filled with sealing agent are necessary and accordingly the above disadvantages of the prior art are fully overcome. Because one connector-side terminal and one bulb-side terminal can be used on several common bulb sockets without exchange, the number of common parts increases even in the manufacture of various kinds of products, thus decreasing a total number of different parts. In addition, each of the terminals is much simpler in shape than the conventional integral-type terminal, and therefore in the manufacture of the bulb socket, an automation system using a part feeder.can be employed. Even if an insert molding is partially used, the dimensional accuracy of the terminals can be made high because of the simple shape of the terminals, and a flow of a resin in the terminals during the insert molding, the deformation of the terminal by interference with a mold, and an improper flow of the resin will hardly occur. In the production method according to the present invention the two kinds of terminals are fixed by press-fitting, and an improper flow of the resin as experienced in the insert molding is eliminated. In addition, the cost can be reduced by an automation system employing a part feeder. As described above, in the bulb socket of the present invention, the material can be selected so as to satisfy the characteristics required for each terminal, thereby achieving a high performance design. In addition, although the number of the component parts for one kind of bulb socket increases, the number of common parts for various kinds of such bulb sockets increases, and therefore the number of all the parts will not greatly increase, and the production cost can be reduced, for example, by the use of an automation system employing a part feeder. Moreover, insert-molding defects, as encountered with the insert molding of an integral-type terminal of a complicated shape are eliminated, thereby ensuring a high-quality design. Moreover providing a recess in the socket housing, filling said recess with a sealing agent after insertion and connection of the terminals and waiting for the sealing agent to get cured is no longer reqired. In the production method of the present invention, the cost reduction can be achieved by the use of an automation system, and high-quality design can be achieved by elimination of molding defects. These and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a vertical cross-sectional view of a housing body of one preferred embodiment of the present invention; Fig. 2 is a front-elevational view of the housing body; Fig. 3 is a cross-sectional view taken along the line III-III of Fig. 2; Fig. 4 is a perspective view of a connector-side terminal; Fig. 5 is a plan view of a connector-side terminal; Fig. 6 is a perspective view of a bulb-side terminal; Fig. 7 is a side-elevational view of bulbside terminal; Fig. 8 is a plan view of a bulb-side terminal; Fig. 9 is a cross-sectional view showing the two kinds of terminals attached to a housing body; Fig. 10 is a vertical cross-sectional view showing the two kinds of terminals attached to a housing body; Fig. 11 is a front-elevational view of an embodiment of the present invention; Fig. 12 is a cross-sectional view taken along the line XII-XII of Fig. 11; and Fig. 13 is a perspective view showing a wedge base-type bulb. A preferred embodiment of the present invention will now be described with reference to the drawings. A bulb socket of this embodiment is adapted to hold a wedge base bulb B (hereinafter referred to merely as "bulb B") of the single filament type shown in Fig. 13. The bulb B is of a conventional construction and includes a flat base portion 3 of glass integrally connected to a lower end of a bulb body 2 containing a filament 1. Two lead wires 4, extending from a lower end of the base portion 3, are folded back respectively on opposite (right and left) sides of the base portion 3 to form feeder terminals 5, and projections 6 and 7 are formed on the right and left sides of the base portion 3, respectively. A housing body 11 of the bulb socket is made of a plastic material and includes a socket housing 12 for receiving the base portion 3 of the bulb B and a connector housing 13 for receiving a feeder connector (not shown), 'as shown in Fig. 1. The bulb socket is fixedly mounted on a mounting plate (not shown) held between a flange 14 and an engagement projection 15, which are formed on the outer periphery of the socket housing 12. The socket housing 12 and the connector housing 13 are open respectively in directions perpendicular to each other. The bulb socket is of an L-shape as a whole, as viewed from the side thereof. Terminal insertion cavities 16 are formed in an inner end surface of the connector housing 13, as shown in Figs. 2 and 3, and press-fit grooves 17 are formed in continuous relation to each terminal insertion cavity 16, respectively. A communication cavity 18 is formed in an inner end portion (bottom portion) of the socket housing 12, and is in communication with the terminal insertion cavities 16 in the connector housing 13. Two kinds of terminals, that is, two connector-side terminals 20 of the same shape and two bulb-side terminals 30 of the same shape, are mounted on this bulb socket, and these terminals will be described below in detail. As shown in Figs. 4 and 5, the connector-side terminal 20 is L-shaped as a whole and has a connector tab portion 22 for connection to a receptacle (not shown) of the feeder connector and a relay tab portion 21 extending perpendicularly from the connector tab portion for connection to the bulb-side terminal 30. A pair of press-fit projections 23 are formed on and extend respectively from opposite (right and left) edges of a proximal end portion of the connector tab portion 22 (which is adjacent to a bent portion), assuming a wing-like configuration. A retaining portion 23a is formed on a distal end of each of these press-fit projections. This connector-side terminal 20 is formed of an electrically-conductive material having a plate thickness, for example, of about 0.64 mm so that the connector tab portion 22 can have optimal characteristics. The bulb-side terminal 30 is shaped as shown in Figs. 6 to 8, and these terminals 30 are provided in the socket housing 12 at corner portions thereof in opposed relation to each other. An upper portion of the terminal 30 defines a bulb contact portion 31 bent into an L-shape as viewed from the top, and functions to mechanically hold the base portion 3 of the bulb B, and also functions to electrically contact the lead wire 4. More specifically, each of these bulb contact portions has a bulged, stamped resilient holder portion 32 adapted to be held respectively against the right and left sides of the base portion 3. Also, each bulb contact portion has a resilient clamping portion 33 formed by bending, these clamping portions 33 being adapted to be held respectively against the front and rear sides of the base portion 3. A feeder electrode 34, which is downwardly bent or directed, is provided at a level below the resilient clamping portion 33. The feeder electrode 34 contacts the lead wire 4, with the base portion 3 mechanically held by the bulb contact portion 31. Two retaining pieces 35 are formed respectively on opposite sides of the resilient holder portion 32, each retaining piece 35 being formed by stamping in a manner to provide an upwardly-open portion. The bulb-side terminal 30 is formed of an electrically-conductive material having a plate thickness, for example, of about 0.4 mm so that this terminal 30 can provide a sufficient force to hold the base portion 3 of the bulb B and also can provide a proper contact pressure with the lead wire 4. A relay terminal portion 36 is formed at a lower end of the bulb contact portion 31 by bending each of right and left side portions of a downwardly-extending relay conductor 37 into an arcuate cross-sectional shape, thus providing a so-called receptacle configuration. This relay terminal portion 36 can be press-fit on the relay tab portion 21 of the connector-side terminal 20 from the upper side to be connected thereto. Next, a method of producing the bulb socket of the above construction will be described. The two kinds of terminals, that is, the connector-side terminals 20 and the bulb-side terminals 30, are made of predetermined materials, respectively. The housing body 11, having the socket housing 12 and the connector housing 13, which are integral with each other, is formed of a plastic material, for example, by injection molding. At this time, an insert molding (in which terminals are beforehand set in a mold) as used in the conventional construction is not carried out, and therefore a resin can flow satisfactorily, so that the terminals will not be deformed. After the molding of the housing body 11, the two connector-side terminals 20 are press-fitted into the connector housing 13. Here, the connector-side terminal 20 is inserted into the terminal insertion cavity 16, with the relay tab portion 21 directed inwardly, and the two press-fit projections 23, formed at the proximal end portion of the connector tab portion 22, are press-fitted in the press-fit grooves 17, respectively. At this time, the press-fit projections 23 are forced respectively into the press-fit grooves 17, and the retaining portions 23a bite the inner surfaces of the press-fit grooves 17, so that the connector-side terminal 20 is fixed within the connector housing 13 against withdrawal. In this condition, the connector tab portion 22 of the connector-side terminal 20 is extended in a recumbent manner within the connector housing 13, whereas the relay tab portion 21 is extended upwardly in the communication cavity 18. Then, the two bulb-side terminals 30 are incorporated into the socket housing 12 of the housing body 11. Here, the bulb-side terminal 30 is inserted into a predetermined position in the socket housing 12, with the relay terminal portion 36 directed downwardly, and the relay terminal portion 36 is pushed down from a position just above the relay tab portion 21. As a result, the relay terminal portion 36 is spread by the relay tab portion 21, and they are fitted together, thereby connecting the connector-side terminal 20 and the bulb-side terminal 30 together mechanically and electrically. In this condition, the relay terminal portion 36 is connected to the relay tab portion 21, and the retaining pieces 35 of the bulb-side terminal 30 bite the inner peripheral surface of the socket housing 12. Therefore, the bulb-side terminal 30 is fixed within the socket housing 12 against withdrawal, and the bulb socket is completed. As described above, in this embodiment, the terminals mounted within the housing body 11 are the two kinds of terminals, that is, the connector-side terminals 20 and the bulb-side terminals 30. Therefore, the connector-side terminal 20 can be formed of an electrically-conductive material having a plate thickness, for example, of about 0.64 mm so that the connector tab portion 22 can have the best characteristics, and the bulb-side terminal 30 can be formed of an electrically-conductive material having a plate thickness, for example, of about 0.4 mm so that this terminal 30 can provide a sufficient force to hold the base portion 3 of the bulb B and can provide a proper contact pressure with the lead wire 4. Therefore, the material can be selected so as to satisfy the characteristics required for each of the terminals 20 and 30, and therefore the bulb socket can have a high performance. With respect to this type of bulb socket, there have been provided various kinds of products of different specifications, depending on the kind of the mating connector and the kind of the bulb B. Conventionally, the terminals have been different in shape from one product to another, and therefore it has been necessary to prepare many different kinds of terminals, which has greatly increased the number of parts. However, in this embodiment, the connector-side terminals 20 and the bulb-side terminals 30 can be used on a common bulb socket without exchange, and the number of common parts increases even in the manufacture of various kinds of products, thus decreasing a total number of the parts. In addition, each of the terminals 20 and 30 is much simpler in shape than the conventional integral-type terminal. Therefore, in the step of press-fitting the connector-side terminal 20 and in the step of incorporating the bulb-side terminal 30, a part feeder can be used for conveying the terminals 20 and 30. Therefore, although the number of the terminals for one kind of product is larger as compared with the conventional construction using the integral-type terminal, a cost reduction effect, achieved by an automation system using a part feeder, suppresses the cost increase due to an increased number of the parts, and the overall cost is lower. The present invention is not limited to the embodiment described above and shown in the drawings, and for example the following modifications can be made. (a) With respect to the production procedure, although after the connector-side terminals are press-fitted in the connector housing, the bulb-side terminals are incorporated into the socket housing, there can be used a reverse production procedure in which the bulb-side terminals are press-fitted and fixed in the socket housing, and the connector-side terminals are incorporated into the connector housing. In this case, also, the two mating terminals are electrically connected together through the relay terminal portion. (b) In the above embodiment, although the two kinds of terminals are fixed to the housing body by press-fitting or insertion, one terminal may be integrally attached to the housing body by insert molding, and the other terminal may be fixed to the housing body by press-fitting or insertion. Even if the insert molding is thus partially used, the separate-type terminals are simpler in shape than the conventional integral-type terminal, and the deformation of the terminals by interference with a mold, as well as an improper flow of a resin, will hardly occur. Because of the use of the separate-type terminals, an automation system employing a part feeder can be used, so that the cost can be reduced. Thus, the intended object of the present invention can be achieved. (c) In the above embodiment, although a bulb socket for holding the wedge base bulb is shown, the invention can be similarly applied also to a bulb socket for holding a bulb having a metal base. (d) In the bulb socket having the housing body 11 of a generally L-shape as in the above embodiment, the shape of terminals is more complicated as compared with a linear-type socket having a downwardly-open connector housing, and therefore the effects of the invention are most advantageous. However, the invention can, of course, be applied to such a linear-type bulb socket. Furthermore, the present invention can be applied not only to the socket for a bulb of the single filament-type but also to a socket for a bulb of the double filament-type, and many other modifications can be made without departing from the scope of the invention as defined by the appended Claims.

Claims: A bulb socket for holding a bulb (B) and for providing an electrical connection between a feeder connector and an electrical lead on the bulb (B), comprising: an L-shaped housing body formed of an electrically insulative material, said housing body comprising: a connector housing portion (13) connectable with a feeder connector, a socket housing portion (12) for receiving and retaining said light bulb (B), and a connecting cavity (18) connecting the connector housing portion (13) and the socket housing portion (12), wherein a longitudinal axis of the connector housing portion (13) is substantially perpendicular to a longitudinal axis of the socket housing portion (12); at least one electrically conductive connector-side terminal (20) mounted in the connector housing portion (13) and connectable with said feeder connector, and having a relay tab portion (21) extending into the connecting cavity (18); and at least one electrically conductive bulb-side terminal (30) mounted in said socket housing portion (12) and comprising: a feeder electrode (34) for contacting an electrical lead on said bulb (B) inserted in the socket housing portion (12), and a relay terminal portion (36) extending into the connecting cavity (18) and being electrically connected to said relay tab portion (21), characterized in that terminal grooves (17) are integrally formed in the connector housing portion (13) and wherein the at least one connector-side terminal (20) further comprises projections (23) that are press-fittable into said grooves (17) to mount the connector-side terminal (20) in the connector housing portion (13). The device of claim 1, wherein the at least one bulb-side terminal (30) further comprises a clamping- portion (33) for retaining said bulb (B) inserted into the socket housing portion (12). The device of claim 1 or 2, wherein the at least one bulb-side terminal (30) further comprises a resilient holder portion (32) for engaging and retaining said bulb (B) inserted into the socket housing portion (12). The device of anyone of claims 1 to 3, wherein the at least one bulb-side terminal (30) further comprises at least one retaining projection (35) extending from the at least one bulb-side terminal (30) for engaging an interior wall of the socket housing portion (12) to retain the at least one bulb-side terminal (30) in the socket housing portion (12). The device of anyone of claims 1 to 4, wherein the at least one connector-side terminal (20) includes a connector tab portion (22) connectable to a feeder connector and wherein the relay tab portion (21) extends from the connector tab portion (22) into the connecting cavity (18) at an angle of approximately 90°. A method of producing a bulb socket for holding a bulb (B) and for providing an electrical connection between a feeder connector and an electrical lead on the bulb (B), comprising: providing an L-shaped housing body formed of an electrically insulative material, said housing body comprising: a connector housing portion (13) connectable with a feeder connector, a socket housing portion (12) for receiving and retaining said light bulb (B), and a connecting cavity (18) connecting the connector housing portion (13) and the socket housing portion (12), wherein a longitudinal axis of the connector housing portion (13) is substantially perpendicular to a longitudinal axis of the socket housing portion (12); mounting at least one electrically conductive connector-side terminal (20) in the connector housing portion (13) for connection with said feeder connector such that a relay tab portion (21) of said connector-side terminal (20) extends into the connecting cavity (18); and mounting at least one electrically conductive bulb side terminal (30) in said socket housing portion (12) such that a feeder electrode (34) for contacting an electrical lead on said bulb (B) inserted in the socket housing portion (12) extends into said socket housing portion (12) and a relay terminal portion (36) for an electrical connection with said relay tab portion (21) extends into said connecting cavity (18), said method being furthermore characterized by forming terminal grooves (17) in said connector housing portion (13) upon providing said L-shaped housing body, forming projections (23) at the at least one connector-side terminal (20), and press-fitting said projections (23) into said grooves (17) to mount the connector-side terminal (20) in the connector housing portion (13). The method of claim 6, further comprising the steps of: providing mounting slots in the connector housing; and press-fitting the connector-side terminal (20) into the mounting slots to mount the connector-side terminal (20) in the connector housing. The method of claim 6 or 7, further comprising the steps of: bending first and second portions of the relay terminal portion (36) of said bulb-side terminal (30) into an arcuate shape to form a mounting receptacle on the relay terminal portion; and mounting the bulb-side terminal (30) in the socket housing so that said corresponding connector-side terminal (20) is inserted into the receptacle of the relay terminal portion during mounting of the bulb-side terminal (30). The method of anyone of claims 6 to 8, further comprising the steps of: bending first and second portions of the relay terminal portion (36) of said bulb-side terminal (30) into an arcuate shape to form a mounting receptacle on the relay terminal portion; and mounting the connector-side terminal (20) in the connector housing so that the connector-side terminal (20) is inserted into the receptacle of the relay terminal portion (36) of the bulb-side terminal (30) during mounting of the connector-side terminal (20). The method of anyone of claims 6 to 9, further comprising the step of: automating the method of producing a bulb socket with a part feeder for feeding at least one of connector-side terminal (20) and the bulb-side terminal (30).

Inventors: OGAWA SHINJI, OGAWA, SHINJI, OGAWA, SHINJI, C/O SUMITOMO WIRING SYSTEMS LTD.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1994
Main classification: H01R33
IPC codes: H01R43, H01R33